Q. Can something travel faster than speed of light? 

Discussion:

Speed seems to be a relative concept. We can measure(in theroy) speed of light. Some say travel faster than speed of light and you can time travel. Others say not possible. Lets talk theroy. A beam of light leaves a star in a straight line. It travels by a body that is stationary. It passes that body at apprx. 186,000 mi / s. Now say the same beam continues to travel by a object traveling in the exact same path(parallel) however the object is moving at a speed on 185,000 mi/s (remember, this is just a theroy). Now the object is only traveling 1,000 mi/s slower tham this beam. So, could the object travel an additional 185,000 m/s before it started traveling at the speed of light? Of course to a stationary object it would be traveling @ 2x speed of light.......  

Another question about speed.

What would the bullet do?

Travel in an airplane in a straight line at 1000 miles per hour. In a straight line out of the back of plane fire a bullet that travels 1000 miles per hour. To a person on the ground would the bullet seem to float or stay suspened in that space? Of course for a sort time. 

leroy37 : The concept of Relativity requires you to rethink the manner velocities are vectored, at higher velocities, those approaching the speeds where you would think the end result would be, at or above, the speed of light, because the magnitude of these velocity greatly expands the difference in the principles of Einsteinian Physics, over that of  Newtronian Physics, and  it becomes more obviously impossible, for an object of mass, to reach the velocity of light, within this frame of reference, due to the necessary relative energy required, determined by an equation provided by Relativistic Physics. 

 I'm oversimplifying, but the short answer is that the speed of light (in a vacuum) is constant, even if its source is moving.

Projectiles fired from planes are probably a little complicated so I'd leave that to anyone with more physics chops than me. But for a more basic version, if you're rowing a boat at 1mph on a stream that's moving 1mph, then you're travelling 2mph relative to someone standing on the bank. So generally you would add the velocties, but the speed of light is more of an upper limit. As Primordial said, it would be inconsistent with the rest of relativity for something to exceed that speed.

leroy37:

... Another question about speed.

What would the bullet do?

Travel in an airplane in a straight line at 1000 miles per hour. In a straight line out of the back of plane fire a bullet that travels 1000 miles per hour. To a person on the ground would the bullet seem to float or stay suspened in that space? Of course for a sort time. 

While this doesn't have anything to do with general or special relativity (since the velocity is low), it is relative to the observer:

The tail gunner in the plane would see the bullet recede at a speed of 2,000 miles per hour.

A person on the ground would see the bullet moving at 1,000 miles per hour.

To make this an easier problem to solve, make a diagram by marking a straight line five equidistant cross marks. Label the center one "0" and the two adjacent to it with "1" and the two end points "2" ... off to one side make an X.

Let the line mark the path of the plane and bullet and the X denote an observer on the ground.

At 0, the gun fires. After one interval, the plane is at one of the 1 marks and the bullet is at the other. After two intervals, the plane is at one of the 2 marks and the bullet is at the other.

From the standpoint of the plane, each interval takes it 2 marks from the bullet, and vice versa.

From the standpoint of the observer, each interval takes the plane, and the bullet, one mark.

I appreciate your post. Certainly the Theory of Relativity and others dictate specific laws. Thus far they appear to be correct in our application of these laws. However, I believe there are things we think we know and really have no way to prove or disprove. I believe there are things we cannot explain, know, or understand at this point in our evolution. I certainly do not know it all and probably know very little. However, speed, what ever the amount is nothing more than something passing something else. Very hard for me to grasp that 186,000 m/s is the magical number that cannot be crossed. Thanks for the discussion.

I think what he meant is if the plane were travelling at 1000km/h, and you shot a bullet which travels at the same speed in the opposite direction of the plane, to a static observer it would appear to be stationary, however to an observer on the plane, would it appear at 1000km/h, or 2000km/h?

To me it seems to make sense that it would appear to be travelling 1000km/h away from the plane, since that is the speed of the plane relative to the ground, and since the bullet is stationary relative to the ground, it should only be 'moving' 1000km/h.

Please correct me if this is wrong.

The bullet is stationary ONLY relative to itself.

When you launch a projectile from a tube, it exits the tube at its rated muzzle velocity no matter what the external conditions may be. What happens after that depends on those external conditions (for example, what happens when you hold the muzzle against a stone wall?).

To an observer on the ground, the plane and its attached gun both appear to be moving at the same speed. When the gun fires, the bullet leaves the muzzle at its rated velocity and that is how the ground-based observer perceives it.

Maybe this diagram will help (it assume the plane and bullet are moving at 1,000 feet/second):

At t=0 ("bang"), the bullet just leaves the muzzle of the gun. If the ground-based observer had very good eyesight, he'd see the bullet at the muzzle. One second later (t=1), the plane has moved 1,000 feet to the left of the observer and the bullet has moved 1,000 feet to the right (of the plane's tail). But the plane's tail is now 1,000 feet to the left. So, to the observer, the plane and the bullet are now separated by 1,000 feet. Each appears to him to be moving at 1,000 feet per second. But to the tailgunner -- for whom the plane appears to be stationary, since he's in it -- the bullet appears to be receding from him at 2,000 feet per second (it's 2,000 feet from the plane after only one second). To  the observer on the ground, the bullet appearst o be falling straight down (absent any effects from winds aloft).

Edit: Yep, Curt's right (see below). I forgot the 1,000 ft/second is relative to the plane's tail (gun's muzzle). A simple vector diagram shows the proper motion.

So if a plane is travelling at 1000 km/h, how fast would the bullet have to be to look 'stationary' to a ground based observer, and be falling straight down?

leroy37:

So, could the object travel an additional 185,000 m/s before it started traveling at the speed of light?

I assume you meant mi/s (miles per second) and not m/s (meters per second).  That being said, mi/s is a unit of velocity and not distance, which makes the quoted sentence difficult to comprehend.

In 1887 Albert Michelson and Edward Morley conducted an experiment designed to measure the speed of light coming from a particular star at various points in the Earth's orbit.  The great surprise was that no matter which direction the Earth was moving, the measured speed of the light was always exactly the same.

No object with mass can attain the speed of light from the point of view of an outside observer (and certainly not twice the speed of light).  Although it is possible from the perspective an observer in a space ship travelling near the speed of light to reach a destination in far fewer years than the number of light-years that originally separated them.  Light would always appear to be moving at the standard speed of light for the space traveler and the ground based observer.  These are the conclusions of Albert Einstein’s 1905 theory of special relativity.  Here’s a Wikipedia link:  http://en.wikipedia.org/wiki/Special_relativity

Regarding a bullet fired with a muzzle velocity of 1000 mi/hr out of the back of a plane that was traveling 1000 mi/hr relative to the ground:  to a ground based observer the bullet would momentarily appear still before plummeting straight to the ground due to the pull of gravity.  When objects are moving at velocities that are quite small compared with the speed of light, normal vector arithmetic will suffice.  But at higher velocities counterintuitive relativistic effects must be calculated with more complicated mathematics.

I was right! Woohoo!

ChipdatajeffB, I was worried after reading your post, because I really didn't understand what you were saying. I thought for a minute that I had to completely re-think my understanding of moving bodies. Thank you for editing your post for the benefit of future readers.

Thank you Centaur for clearing this up.

Clear skies